Polyketides are a diverse group of natural products which include many compounds useful as drugs. They are assembled by condensation of acetate/malonate units followed by a variety of subsequent modifying reactions. The mechanism of the initial cyclization is still incompletely understood. This project addresses various aspects of polyketide biosynthesis including the steric course of the initial condensation reaction. This will be studied using stereospecifically 13C and 3H-labelled malonic acid of R and S configuration. This compound will be synthesized from an appropriately 13C-labelled precursor, epoxysuccinic acid, by opening of the epoxide ring with supertritide, followed by permanganate oxidation to malonate. The resulting malonate samples will be used to determine the overall stereochemical course of the formation of the polyketides, 6-methylsalicyclic acid and orsellinic acid and the chalcone, naringenin. The results will give insight into the chemical mechanism of this key carbon-carbon bond forming process. In addition, in a collaboration with the group of Professor Yu Sam Kim, Seoul, we will study the stereochemistry of malonate metabolism by several microbial enzymes. User Details: Experiment Details: User Number: 1614 Tritiation City, State: Seattle, WA NMR Funding Source: NIH 5 R01 AI 20264-16 Tritides and NSF INT-9604888 2 days Charge: $4188.59 2 compounds Program Income: $4187.89 Secondary User: Professor Yu Sam Kim Seoul, North Korea